TEMPO



TEMPO
Other names 2,2,6,6-Tetramethyl-piperidin-1-oxyl
Identifiers
CAS number 2564-83-2
RTECS number TN8991900
Properties
Molecular formula C9H18NO
Molar mass 156.25 g/mol
Melting point

36-38 °C

Boiling point

sublimes under vacuum

Hazards
MSDS External MSDS
R-phrases R34
S-phrases S45
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

2,2,6,6-Tetramethylpiperidine-1-oxyl or TEMPO is the organic synthesis, and as an initiator in polymer chemistry.[3] The stability of this radical is attributed to the steric protection provided by the four methyl groups adjacent to the nitroxyl group.[4]

Application in organic synthesis

TEMPO is employed in hypochlorous acid generates the N-oxoammonium salt from the TEMPO.

One typical reaction example is the oxidation of (S)-(-)-2-methyl-1-butanol to (S)-(+)-2-methylbutanal.[5] 4-Methoxyphenethyl alcohol is oxidized to the corresponding chemoselectivity, being inert towards a secondary alcohols, but the reagent will convert aldehydes to carboxylic acids.

In cases where secondary oxidizing agents cause side reactions, it is possible to stoichiometrically convert TEMPO to the oxoammonium salt in a separate step. For example in the oxidation of geranial 4-acetamido-TEMPO is first oxidized to the oxoammonium tetrafluoroborate.[7]

References

  1. ^ Barriga, S (2001). "2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)". Synlett (4): 563. doi:10.1055/s-2001-12332.
  2. ^ Lebelev, O. L.; Kazarnovskii, S. N. Zhur. Obshch. Khim. 1960, volume 30, page 1631ff.
  3. ^ Montanari, F.; Quici, S.; Henry-Riyad, H.; Tidwell, T. T. “2,2,6,6-Tetramethylpiperidin-1-oxyl” Encyclopedia of Reagents for Organic Synthesis; John Wiley & Sons, 2005. DOI: 10.1002/047084289X.rt069.pub2
  4. ^ Zanocco, A. L.; Canetem., A. Y.; Melendez, M. X. (2000). "A Kinetic Study of the Reaction between 2-p-methoxyphenyl-4-phenyl-2-oxazolin-5-one and 2,2,6,6-Tetramethyl-1-piperidinyl-n-oxide". Bol. Soc. Chil. Quím. 45: 123-129.
  5. ^ P. L. Anelli, F. Montanari, S. Quici. "A General Synthetic Method for the Oxidation of Primary Alcohols to Aldehydes: (S)-(+)-2-Methylbutanal". Org. Synth.; Coll. Vol. 8: 367. 
  6. ^ Zhao, M. M.; Li, J.;Mano, E.; Song, Z. J.; Tschaen, D. M.. "Oxidation of Primary Alcohols to Carboxylic Acids with Sodium Chlorite catalyzed by TEMPO and Bleach: 4-Methoxyphenylacetic Acid". Org. Synth. 81: 195. 
  7. ^ Bobbitt, J. M.; Merbouh, N.. "2,6-Octadienal, 3,7-dimethyl-, (2E)-". Org. Synth. 82: 80. 
 
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